Icing on aerodynamic surfaces occurs due to the accumulation of rain droplets when the surrounding temperature is below the freezing temperature. It is well known that icing phenomenon alters the aircraft aerodynamic forces and may cause serious damage. Therefore, studying water droplet behavior, such as shedding and coalescence serves as the primary step which can lead to understanding the fundamental physics of aircraft icing. Hence, in this study an experimental approach is used to investigate the shear-driven droplet shedding and coalescence on a hydrophilic substrate which can serve as the building block for the formation of rivulets.
Holl M, Patek Z and Smrcek L. Wind tunnel testing of performance degradation of ice contaminated airfoils. In: Proceedings of the 22nd international congress of aeronautics sciences, Harrogate, UK, 27 August to 1 September 2000, paper no. 3.1.1, pp.1–7.
2.
MilneAJBAmirfazliA. Drop shedding by shear flow for hydrophilic to superhydrophobic surfaces. Langmuir2009; 25: 14155–14164.
3.
LeeMWKangDKYoonSS. Coalescence of two drops on partially wettable substrates. Langmuir2012; 28: 3791–3798.
4.
DucheminLEggersJJosserandC. Inviscid coalescence of drops. J Fluid Mech2003; 487: 167–178.
5.
BrandesAZhangGVivekanadanJ. Drop size distribution retrieval with polarimetric radar model and application. J Appl Meteorol2004; 43: 461–475.
6.
BradleySGStowCD. Collisions between liquid drops. Phil Trans R Soc Lond A1978; 287: 635−675–635−675.
7.
Martinez-DavalosAANunezR. Coalescence of liquid drops by surface tension. Phys Rev E2001; 63: 046309–046309.
8.
WhiteEBSchmuckerJAJ. A runback criterion for water drops in a turbulent accelerated boundary layer. J Fluids Eng2008; 130: 061302–061302.
9.
MoghtadernejadSMohammadiMJadidiM. Shear driven droplet shedding on surfaces with various wettabilities. SAE Int J Aerosp2013; 6: 459–464.
10.
ThoroddsenSTTakeharaKEtohTG. The coalescence speed of a pendant and a sessile drop. J Fluid Mech2005; 527: 85–114.
11.
NarheRDBeysensDAPomeauY. Dynamic drying in the early-stage coalescence of drops sitting on a plate. Europhys Lett2008; 81: 46002–46002.
12.
FarhangiMGrahamPJChoudhuryNR. Induced detachment of coalescing droplets on superhydrophobic surfaces. Langmuir2011; 28: 1290–1303.
13.
GrahamPJFarhangiMDolatabadiA. Dynamics of droplet coalescence in response to increasing hydrophobicity. Phys Fluids2012; 24: 112105–112105.
14.
FrenkelJ. Viscous flow of crystalline bodies under the action of surface tension. J Phys (Moscow)1945; 9: 385−391–385−391.
15.
RistenpartWDMcCallaPDRoyRV. Coalescence of spreading drops on a wettable substrate. Phys Rev Lett2006; 97: 064501–064501.
16.
Moghtadernejad S, Jadidi M, Tembely M, et al. Concurrent droplet coalescence and solidification on surfaces with various wettabilities. In: Proceedings of the 4th joint US-European fluids engineering summer meeting, Chicago, IL, 2014.
17.
AntoniniCInnocentiMHornT. Understanding the effect of superhydrophobic coatings on energy reduction in anti-icing system. Cold Reg Sci Technol2011; 67: 58–67.
18.
JungSTiwariKDoanV. Mechanism of supercooled droplet freezing on surfaces. Nat Commun2012; 3: 615–615.
19.
PashininA. Effect of wettability on sessile drop freezing: When superhydrophobicity stimulates an extreme freezing delay. Langmuir2014; 30: 1659–1668.
20.
EggersJListerJRStoneHA. Coalescence of liquid drops. J Fluid Mech2000; 401: 293–310.
21.
YarinALOronARosenauP. Capillary instability of thin liquid film on a cylinder. Phys Fluids1993; 5: 91−98–91−98.
22.
AartsDLekkerkerkerHGuoH. Hydrodynamics of droplet coalescence. Phys Rev Lett2005; 95: 164503–164503.
23.
BlasiusH. Grenzschichten in Flüssigkeiten mit kleiner Reibung. Z Math Phys1908; 56: 1–37.
24.
AbramoffMDMagalhãesPJRamSJ. Image processing with ImageJ. Biophoton Int2004; 11: 36–42.
